During the manufacture of instant coffee products from green beans, many aroma and flavor vapors of coffee are produced. Some of these vapors are produced during the roasting and/or grinding of coffee beans. Others are produced upon contact of the roast ground coffee with water as, for example, in the production of aqueous extract. Still other vapors are given off where the aqueous extract is concentrated, as by vacuum evaporation, and under certain conditions of drying, such as spray drying.
Because these vapors are essential for the aroma and flavor of naturally brewed coffee, it is conventional to attempt to collect and reincorporate at least a portion of them into dry instant coffee products. These vapors and many of the means for their recovery are described in the two volumes of Coffee Processing Technology by Sivetz et al., AVI Publishing Company, Inc. (1963), particularly Chapter 14.
These prior art techniques have not, however, been completely successful. Many require apparatus or conditions which have not proven feasible for commercialization. Others do not permit recovery of all vapors important to aroma and flavor. This accounts, in part, for the lower and less complete aroma ordinarily associated with instant, as opposed to freshly brewed, coffee beverage.